The proliferation of the Internet, devices that access it, and consequently, Internet based services are driving an insatiable thirst for computational power. To meet this need, large data centers have been set up. Typical data centers house hundreds, maybe even thousands of servers, and serve as the backbone for a variety of Internet services. The services hosted by data centers typically come with the requirement of high availability, close to 99.9% up time, which is usually supported by replicating servers and maintaining spare capacity. Furthermore, data centers are designed for a peak loads which are both occasional and short lived. As a result, data centers tend to consume large amounts of power. In phases that the data center is not fully loaded, idle servers can be shutdown without substantial loss in performance. When the load increases, powered off servers can be booted-up to service the requests and maintain Quality of Service (QoS).
Reducing the power consumption of a data center contributes to reduced operational expense, and allows the data center operator to invest in newer hardware and supporting infrastructure, to save money and/or to provide improved services to customers. Prior studies have reported that servers can draw close to 60% of their peak power consumption when idle, and that the global electricity costs for data centers have been reported as running into the billions. Therefore, substantial reduction in power consumption can be achieved by shutting down idle servers.